[PATCH v4 2/4] RISC-V: KVM: Detect and expose supported HGATP G-stage modes

[Radim Krčmář]

2026-02-02T22:07:14+08:00, <fangyu.yu at linux.alibaba.com>:
> From: Fangyu Yu <fangyu.yu at linux.alibaba.com>
>
> Extend kvm_riscv_gstage_mode_detect() to probe all HGATP.MODE values
> supported by the host and record them in a bitmask. Keep tracking the
> maximum supported G-stage page table level for existing internal users.
>
> Also provide lightweight helpers to retrieve the supported-mode bitmask
> and validate a requested HGATP.MODE against it.
>
> Signed-off-by: Fangyu Yu <fangyu.yu at linux.alibaba.com>
> ---
> diff --git a/arch/riscv/include/asm/kvm_gstage.h b/arch/riscv/include/asm/kvm_gstage.h
> @@ -75,4 +76,40 @@ void kvm_riscv_gstage_wp_range(struct kvm_gstage *gstage, gpa_t start, gpa_t end
> +enum kvm_riscv_hgatp_mode_bit {
> +	HGATP_MODE_SV39X4_BIT = 0,
> +	HGATP_MODE_SV48X4_BIT = 1,
> +	HGATP_MODE_SV57X4_BIT = 2,

I think it's a bit awkward to pass 9 when selecting the hgatp mode, but
then look for bit 0 when detecting it...
Why not to use the RVI defined values for this UABI as well?

There are only 16 possible hgatp.mode values, so we're fine storing them
in a bitmap even on RV32.

Thanks.